Abstract: Method and apparatus are disclosed for the stable control of electrooptic devices, such as for providing a stable bias point for operation of a lithium niobate interferometer-type modulator. The bias point of the modulator is thermally controlled by providing a selected difference in the temperatures of optical waveguide lengths of the interferometer. Heaters can be disposed with the lithium niobate substrate for transferring thermal energy with the optical waveguide lengths. A thermally conductive element can be disposed adjacent the optical waveguide lengths to act as “heat spreaders” to facilitate providing the selected difference in temperature. The invention also includes phase shifters, attenuators, and other optical devices formed from single and multiple optical waveguide lengths propagating separate optical beams.

Abstract: An all fiber wavelength selective optical switch has one or more 1.times.N input optical couplers 20,120, each having an input signal with a plurality of wavelengths .lambda..sub.1, .lambda..sub.2, .lambda..sub.3. The output signals from the couplers 20,120 are connected to fibers 26,32,126,158 having Bragg gratings impressed therein, each having a central reflection wavelength, and each having a tuner attached thereto for detuning a central reflection wavelength of the gratings from a base wavelength corresponding to a wavelength of the input signal. For a given grating to pass a particular wavelength of the input signal that grating must be detuned. The fibers 26,32,126,158 are also connected to one or more N.times.1 couplers 66,98 to combine input signals from to different input couplers. The switch allows any combination of input wavelengths from any input signal to be selectively switched to one or more output ports.